new ad company to advertise with

As my site is getting larger, im getting more ad companies contacting me wanting to advertise on my site. (yahoo wont accept australians and google banned me 3 years ago)

Basically I am already with 2 ad companies, one which is doing good, the other pays me up front each month. and this new one has said this in the email they just sent me:

Can we do a $3k revshare test to see what works and then go from there?

What does that mean? I didnt want to sound like i didnt know anything when replying lol.

Thanks

Ask him to define the terms for you.